Spherical nucleic acids (SNAs) have emerged as an interesting new class of materials that have shown promise in programmable materials synthesis, bio-detection, and intracellular gene regulation. Such structures are often comprised of a nanoparticle core functionalized with a dense layer of oligonucleotides. The most heavily studied SNA constructs are composed of a gold core functionalized with alkylthiol-modified DNA. Although SNAs made from gold have shown commercial promise as medical diagnostic and research tools and have shown no acute toxicity in vivo,] there are concerns about the potential long term toxicity of gold nanoparticles and their metabolic fate. Consequently, new forms of SNAs that have cores made of biocompatible materials are highly sought after.